1. Field of the Disclosure
This disclosure relates to a liquid crystal display (LCD) device, as well as manufacturing and repairing methods thereof.
2. Description of the Related Art
In general, LCD devices are based on a driving principle employing optical isotropic and polarization properties of the liquid crystal. The liquid crystal molecules are directionally aligned due to their thin and long shape. Also, the molecular alignment of the liquid crystal can be artificially controlled in direction by means of an electric field applied to the liquid crystal.
If the direction of the liquid crystal molecular alignment is arbitrarily adjusted, a light refractive index of the liquid crystal is varied along the changed direction of the molecular alignment due the optical isotropic property of the liquid crystal. As such, the amount of light passing through the liquid crystal is controlled. Therefore, a variety of images can be displayed by an LCD device.
The LCD devices, as described above, include active matrix LCD devices each configured to include thin film transistors and pixel electrodes which are connected to each other and arranged in a matrix shape. The active matrix LCD devices are now being most heavily highlighted, because of their features, such as, high definition and superior display capability for motion picture images.
FIG. 1 is a disassembled perspective view schematically showing an ordinary LCD device. Referring to FIG. 1, the ordinary LCD device 11 includes: an upper substrate 8 configured to include a common electrode 5 formed on a color filter layer which includes a black matrix 6 and sub-color filters 7; and a lower substrate 10 configured to include pixel electrodes 18 each formed in pixel regions P, thin film transistors T used as a switching element, and gate and data lines 16 and 17. A liquid crystal material 30 is filled between the upper and lower substrates 8 and 10.
The lower substrate 10 is called a thin film transistor substrate. The thin film transistors T, which are used as a switching element, are arranged in a matrix shape. More specifically, the thin film transistors T are formed at the intersections of the gate and data lines 16 and 17. The pixel regions P are defined by the gate and data lines 16 and 17 crossing each other.
The gate lines 16 are used to transfer driving pulse voltages to the gate electrodes of the respective thin film transistors T. The data lines 17 are used to transfer signal voltages to source electrodes of the respective thin film transistors T. Also, each of the thin film transistors T is activated by the pulse voltage on its gate electrode and applies the signal voltage on its source electrode to the respective pixel electrode 18. A pixel is driven when a signal voltage corresponding to a liquid crystal driving voltage is applied to its pixel electrode 18 and a lower voltage than the liquid crystal driving voltage is charged into the common electrode 5.
In this manner, the gate lines 16 and the data lines 17 are arranged in a matrix shape on the entire surface of the lower substrate 10, in order to independently drive the plurality of pixel electrodes 18. Such gate and data lines 16 and 17 are used for directly driving the thin film transistors T which correspond to a switching element.
However, defects can be caused in the array substrates with the above components by a variety of factors while the array substrates are manufactured. The defects include a dot defect, a line defect, an abnormally displayed stain, and so on. The dot defect can be caused by a damaged thin film transistor T or pixel electrode 18. The line defect can be caused by a broken line, a short circuit of lines, a damaged thin film transistor T, and others. The damage of the thin film transistor T can be generated by static electricity.
Such defects are dealt with as a more important matter as the display screens of image devices are enlarged. Actually, an image device with only one damaged line can not be dealt with in a valuable product. For example, if any one of the gate and data lines is shortened with another adjacent line, all the thin film transistors T connected to the shortened line are not driven. This defect generated in the array substrate seriously affects the LCD device. Therefore, it must be necessary to repair the damaged lines, in order to prevent the deterioration of a production rate.
On the other hand, the LCD device is recently manufactured in the structure that common lines formed in the same layer as gate lines are recently arranged under data lines, in order to improve an aperture ratio. The common lines are used to shield light leakage domains which can be generated around the data lines.
When the LCD device with the above structure is manufactured, the common and data lines can be shortened with each other through a gate insulation film, which is formed therebetween, due to their material properties or foreign substances. Due to this, all the thin film transistors connected the shortened data line can be not driven, and furthermore the pixel regions can be entirely damaged.